1. Field of the Invention
The present invention pertains to fluid seals. More specifically, it pertains to annular seals for sealing the connection between coaxially aligned members. Still more specifically, it pertains to bore seals of the flexible pressure-energized type.
2. Brief Description of the Prior Art
There are many types of seals or gaskets for sealing between flanges or in other types of connectors. These seals may be broadly categorized as those that seal on the face of the connector and those that seal on the bore. In both categories, sealing may be achieved by crushing or yielding the gasket; by elastically loading a flexible gasket utilizing a soft coating or plating on the seal surface; or by a combination of both. The seals may or may not be pressure energized as dictated by their geometry and location in the connector.
Because of their relatively massive cross-sections, some bore seals require considerably more bolt up loading than do face seals. On the other hand, bore seals may be more economic because of lower manufacturing tolerances. In addition, most bore seals are self-centering, whereas face seals are generally extremely sensitive to misalignment. Flexible bore seals are particularly adaptable to high temperature use because they are radially compressed during make-up, resulting in residual seal loading.
An extremely popular bore seal of the past few years is one which comprises a flange portion having oppositely disposed flexible lips and a centrally disposed rib portion. The lips are provided with annular seating surfaces which taper outwardly toward the rib portion. Examples of this type of bore seal may be seen in U.S. Pat. Nos. 2,766,829; 2,766,998; 2,766,999; and 3,325,176. While this type of seal is basically a bore seal, it has some of the characteristics of a face seal, due to the rib portion which is normally disposed between the end faces of the connectors with which it is used. Consequently, it requires higher manufacturing tolerances and is more expensive to manufacture than some bore seals.